(a) Field of the invention:
This invention relates to a retinal camera adapted to a group examination.
(b) Description of the prior art:
The advent of a highly aged society is recently anticipated and the importance of an ophthalmoscopy which is effective to the medical examination and diagnosis of high age diseases tends to increase year by year. Under such circumstances, the demand for a retinal camera easily photographing retinal images in a collective medical examination is conspicuous. Generally, when photographing retinal images with a retinal camera in a collective medical examination, it is usual to use 35 mm-films in view of the necessity that retinal images of many persons must be photographed and the fact that clear photographs can be taken. However, only after the 35 mm-film is developed and enlarged, that is after the collective medical examination, will it be known whether the retinal image is properly photographed or not. Thus, this is typically known only several days after the medical examination ends. In case the photographing fails, the examinee must be called on again or must come to the medical establishment, causing much trouble and waste of time.
As one of the solutions of such problems, conventionally, as shown in Japanese Preliminary Patent Publication No. Sho 52-69617, a means for sensing whether the examinee has opened or closed their eyelid is provided, so that whether the eyelid is opened or closed can be indicated. When the eyelid is closed, the photographing means will be made inoperative to avoid any failure of photographing when the eyelid of the examinee is closed.
As another conventional example, as shown, for example, in Japanese Preliminary Patent Publication No. Sho 57-183830, a retinal camera having an image pickup means also include a photographing light branching means on a photographing light path. This allows at least a part of the photographing light to be led to the image pickup means. This photographing light is indicative of the retinal image recorded on the film, and may be indicated on such means as, for example, a monitor on the basis of the output of the image pickup means and whether a flare or the like is mixed in or not may be confirmed on the spot.
However, in the retinal camera shown in the above-mentioned Japanese Preliminary Patent Publication No. Sho 52-69617, an estimate must be made on the basis of whether the reflected light amount from the examined eye abnormally increases or not, and therefore a photographing failure will be unavoidable when the eye of the examinee moves momentarily, the center of the pupil and the optical axis of the photographing system are displaced from each other and the reflected light from the examined eye reduces. The retinal camera shown in the above-mentioned Japanese Preliminary Patent Publication No. Sho 57-183830 is a positive means by which the same as the photographed image can be observed but requires an image pickup tube for visible light only to confirm retinal images to be photographed, requires an image pickup tube for a visible light also in the case of an observing system with an infrared ray illumination and thus has a defect in that the retinal camera is made expensive and large.